Author:
GRIFFITHS ROSS W.,FINK JONATHAN H.
Abstract
In a previous study of the effects of cooling and solidification
on
flows issuing onto a
horizontal plane and spreading under gravity we considered the case of
a viscous fluid
that solidifies to form a thin surface crust with a finite yield strength.
In that case, the
coupling of solidification and viscous stresses in the flow led to
a sequence of flow
regimes or styles of flow and crustal deformation. Here, we study
the spreading, from
a small source, of a plastic material having a yield strength before
cooling. In this case
the fluid again begins to freeze as it spreads radially under
gravity, and forms a dome
having a surface crust which is stronger than the extruded fluid.
If cooling is sufficiently
rapid compared to gravity-driven spreading, the flow is found to be controlled
by
solidification. The flow again takes on one of a number of flow regimes
depending on
the pace of solidification relative to the rate of lateral flow, or extrusion
rate.
However, these flow regimes are quite different from those
for the viscous extrusions,
implying that the internal yield stress has a strong influence on
the behaviour. Styles
of flow ranged from inflation of an axisymmetric dome to irregular
extrusion of lateral
lobes and vertical spines. These qualitatively different regimes have much
in common
with the eruption styles of volcanic lava domes produced by effusion of
extremely
viscous silicic magmas which may possess a yield strength, and the model
provides
information about the factors influencing the morphology and hazards of
such
volcanic flows.
Publisher
Cambridge University Press (CUP)
Subject
Mechanical Engineering,Mechanics of Materials,Condensed Matter Physics
Cited by
85 articles.
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